Raster Tiles

<!--
  示例：栅格瓦片
  核心逻辑：raster 源加载 256 像素瓦片，滑块调透明度，切换明暗两套瓦片地址
  依赖：MapLibre GL JS 4 · jsDelivr CDN · demotiles 样式 · CARTO 免 Key 栅格瓦片
-->
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta name="robots" content="noindex,follow">
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>栅格瓦片</title>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/maplibre-gl@4/dist/maplibre-gl.css">
<style>
  html,body{height:100%;margin:0}
  body{display:flex;flex-direction:column;overflow:hidden;
       font:13px/1.6 -apple-system,"Segoe UI","PingFang SC",sans-serif;color:#16181d}
  .bar{flex:0 0 auto;display:flex;gap:12px;align-items:center;padding:8px 12px;
       background:#f6f7f9;border-bottom:1px solid #e3e6ea;font-size:12px;color:#58606e;flex-wrap:wrap}
  .bar b{color:#16181d;font-weight:600}
  .bar input[type=range]{width:110px}
  .bar label{display:flex;gap:5px;align-items:center;cursor:pointer}
  #map{flex:1 1 auto;min-height:0}
</style>
</head>
<body>
<div class="bar">
  <label>透明度 <input id="op" type="range" min="0" max="1" step="0.05" value="1"> <b id="opv">1.00</b></label>
  <label><input id="dark" type="checkbox"> 深色瓦片</label>
  <span>tileSize <b>256</b></span>
  <span>缩放 <b id="z">—</b></span>
</div>
<div id="map"></div>
<script src="https://cdn.jsdelivr.net/npm/maplibre-gl@4/dist/maplibre-gl.js"></script>
<script>
(function () {
  'use strict';

  if (typeof maplibregl === 'undefined') {
    document.body.innerHTML =
      '<div style="padding:24px;color:#b42318">MapLibre 加载失败，请检查能否访问 cdn.jsdelivr.net</div>';
    return;
  }

  var LIGHT = ['https://basemaps.cartocdn.com/light_all/{z}/{x}/{y}.png'];
  var DARK = ['https://basemaps.cartocdn.com/dark_all/{z}/{x}/{y}.png'];

  var map = new maplibregl.Map({
    container: 'map',
    style: 'https://demotiles.maplibre.org/style.json',
    center: [104.2, 35.5],
    zoom: 3,
    attributionControl: {
      compact: true,
      customAttribution: 'Tiles © Esri © CARTO'
    }
  });

  map.addControl(new maplibregl.NavigationControl(), 'top-right');

  map.on('load', function () {
    map.addSource('raster-base', {
      type: 'raster',
      tiles: LIGHT,
      tileSize: 256,
      minzoom: 0,
      maxzoom: 19,
      attribution: 'Tiles © Esri © CARTO'
    });

    map.addLayer({
      id: 'raster-base',
      type: 'raster',
      source: 'raster-base',
      paint: {
        'raster-opacity': 1,
        'raster-fade-duration': 120
      }
    });
  });

  document.getElementById('op').addEventListener('input', function () {
    var v = parseFloat(this.value);
    document.getElementById('opv').textContent = v.toFixed(2);
    if (map.getLayer('raster-base')) {
      map.setPaintProperty('raster-base', 'raster-opacity', v);
    }
  });

  document.getElementById('dark').addEventListener('change', function () {
    var src = map.getSource('raster-base');
    if (!src) return;
    src.setTiles(this.checked ? DARK : LIGHT);
  });

  map.on('moveend', function () {
    document.getElementById('z').textContent = map.getZoom().toFixed(2);
  });

  map.on('error', function (e) {
    if (e.error) console.warn('瓦片错误：' + e.error.message);
  });
})();
</script>
</body>
</html>